/Engine/Plugins/Runtime/GeometryProcessing/Source/DynamicMesh/Public/GroupTopology.h
Get the set of selected triangles for a given GroupTopologySelection
void GetSelectedTriangles ( const [FGroupTopologySelection](API\Plugins\DynamicMesh\FGroupTopologySelection) & Selection, [TArray](API\Runtime\Core\Containers\TArray)< int32 > & Triangles ) const